# Freeform scissor cut in 3D segmentation very slow

**URL:** <https://discourse.slicer.org/t/freeform-scissor-cut-in-3d-segmentation-very-slow/29575>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [May 22, 2023, 1:03pm UTC](https://discourse.slicer.org/t/freeform-scissor-cut-in-3d-segmentation-very-slow/29575 "2023-05-22T13:03:54Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![ziri](https://avatars.discourse-cdn.com/v4/letter/z/54ee81/32.png) [@ziri](https://discourse.slicer.org/u/ziri)\
**Post date:** [May 22, 2023, 1:03pm UTC](https://discourse.slicer.org/t/freeform-scissor-cut-in-3d-segmentation-very-slow/29575/1 "2023-05-22T13:03:55Z")

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Hi, I was trying to cut my 3D segmentation map with scissor tool, but it performs very slow: for the scissor-cut task below it takes \>10min. I also disabled surface smoothing in segmentation rendering.

 ![cut3d](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/2/e2ba3c55ca42b4ec5949857953a35c0894411797.jpeg)

My platform: i7-11700k desktop CPU | Windows 10 | Slicer v.5.0.3

 ![Image 003](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/3/c/3c1d1ea2225aef120459efd1df9908c943b13ea6.png)

My data:

 ![Image 005](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/1/c/1c8f7c9f77d714beb465f9b5838e8c8916a5e8cc.png)

I’m also using a 4k monitor so not sure if takes more resources to compute but I tried using a 1080p screen resolution it doesn’t help too much. I appreciate any advice!

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [May 22, 2023, 2:48pm UTC](https://discourse.slicer.org/t/freeform-scissor-cut-in-3d-segmentation-very-slow/29575/2 "2023-05-22T14:48:42Z")

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Recalculating the 3D surface is probably taking all the time. Try turning off 3D and do as much cleanup as you can in the slice views and then turn on 3D when you have less noise in the model.

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**Author:** ![ziri](https://avatars.discourse-cdn.com/v4/letter/z/54ee81/32.png) [@ziri](https://discourse.slicer.org/u/ziri)\
**Post date:** [May 25, 2023, 1:51am UTC](https://discourse.slicer.org/t/freeform-scissor-cut-in-3d-segmentation-very-slow/29575/3 "2023-05-25T01:51:26Z")

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Thanks for the suggestion! This does improve the speed. However, it was not like this slow (\>10min) before (with older slicer version or on a different dataset I’m not sure), so I’m trying to figure out the fundamental issue here.

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<div class="post-metadata">

**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [May 25, 2023, 1:39pm UTC](https://discourse.slicer.org/t/freeform-scissor-cut-in-3d-segmentation-very-slow/29575/4 "2023-05-25T13:39:55Z")

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If you have a chance to experiment with different slicer versions and datasets and can report a reproducible difference in behavior that would be helpful. From looking at your screenshot it appears you have a lot of noise, and those small islands take time to update in 3D on every edit operation is a good workaround.